This invention relates to a process for producing a low gloss agent capable of giving molded articles having a low gloss, the low gloss agents, low gloss thermoplastic resin compositions and molded articles, which can be used in the fields of, for example, internal and external automotive trims, exterior parts of household electric appliances, office automation appliances and the like, and building materials such as gutter, in which not only high heat resistance and impact strength but also low gloss are required.
Thermoplastic resins are utilized for various purposes because of their excellent processability and mechanical properties. The surface of molded articles of these resins usually has a good gloss, but there is also a demand for molded articles having a low surface gloss.
Particularly when a molded article is used as an internal or external automotive trim, its gloss should be sufficiently low to avoid lowering of visibility by reflected light and secure safe driving.
As a method for imparting a low gloss to the surface of molded articles, there have heretofore been known, for example, (1) a method of embossing the surface of a mold, (2) a method of coating a low gloss coating material on the surface of a molded article, (3) a method of mixing a resin with an inorganic filler such as talc, calcium carbonate, mica, etc., (4) a method of mixing a thermoplastic resin with a crosslinked polymer, (5) a method of adding a rubber-like elastomer to a starting resin, and (6) a method of increasing the particle size of a rubber grafted in emulsion polymerization.
The above low gloss imparting methods have, for example, defects described below. In the case of the method of (1), no sufficient low gloss imparting effect can be obtained, and a molded article surface having a complicated shape cannot be embossed. In the case of the method of (2), a coating step costs much, environmental pollution is caused, and the resin surface and physical properties are deteriorated by a solvent. In the case of the methods of (3) and (4), lowering of the impact strength is unavoidable, and the gloss of molded article changes depending on molding conditions including molding pressure, mold temperature, etc., so that no uniform low gloss can be attained. In the case of the methods of (5) and (6), nonuniformity of gloss tends to be caused, weld lines are formed owing to the rubber-like elastomer, and the stiffness and hardness of molded article are deteriorated. Thus, according to the prior art, it has been very difficult to attain both high impact strength and low gloss.
Particularly in attaining an improved heat resistance which is required of internal automotive trims, it is more difficult to maintain the impact strength as in the case of ordinary thermoplastic resins.